1. Field of the Invention
This invention relates to a solid styrene-allyl alcohol based polythiol composition. More particularly, this invention relates to solid, solvent-soluble, curable compositions comprising liquid polyenes-solid polythiols and method of preparing the same, as well as curing the solid polymer composition in the presence of a free radical generator to solid, cross-linked, solvent-insoluble materials. More specifically, this invention relates to solid photoresists and method of preparing same.
2. Description of the Prior Art
It is known that polyenes are curable by polythiols in the presence of free radical generators such as actinic radiation to solid polythioether-containing resinous or elastomeric products. In these prior art polyene-polythiol curable systems, either both the polyenes and polythiol were liquids, or one of the polymeric components was solid and the other liquid. Both liquid curable systems and the liquid-solid curable polymeric systems possess certain limitations and disadvantages. The use of curable liquid systems in preparation of photoimaged surfaces such as relief printing plates and photoresists has many undesirable features such as a time consuming liquid coating operation which involves the use of cumbersome and additional apparatus, particularly expensive liquid dispensing equipment. A particular disadvantage of the liquid polymer systems is the resulting limited resolution during the photoimaging step, since it is necessary to maintain an air gap between the image, e.g., photographic negative and the liquid photocurable composition coated on a surface which is to be imaged in order to avoid marring the image and allowing its reuse.
Additionally, in the manufacture of certain printed circuits, when various photosensitive polymers are applied as liquid photoresists, they clog "thru-holes" in double-sided or multi-layer printed circuits.
Since solid polythiols are not readily available, prior art polyene-polythiol curable systems are composed mostly of solid polyenes and liquid polythiols in which the components are often incompatible, are not easily workable, or do not produce dry films.